I've found the G3 to be great. It's fast, I've found little or no lag (although others do report lag on the G3), I like LG's take on the Android skin, and the general feel in the hand is nice too, considering it is pretty much false plastic.
Like any phone, it's not perfect. It depends what you're after. It has a brilliant camera, but it's not THE absolute best one out there. The battery life is fine, but, due to the screen ppi, it does drop fast if you use it a lot - however, the standby time on the G3 is awesome - so what you might lose when you use the screen a lot, you'll often make up when it's idle - of course, if you hammer the phone, the battery will get munched much quicker - but then the battery is removable so you can always carry a spare - I get 12-16hrs on average, and use it loads.
Personally, I think it's hard to beat the G3 currently if you want a top-end Android handset.